In general, a roller type one-way clutch is constituted by an outer race, an inner race disposed coaxially with the outer race, a plurality of rollers disposed between an outer peripheral surface of the inner race and an inner periphery cam surface of the outer race and adapted to transmit torque, and springs contacted with the rollers at an idle rotation side.
With this arrangement, in the one-way clutch, the inner race is rotated only in one direction with respect to the outer race by a cam mechanism constituted by the roller and the cam surface. That is to say, the inner race is designed so that the inner race is idly rotated with respect to the outer race in one direction and serves to transmit rotational torque to the outer race via the cam mechanism only in the opposite direction.
In general, in the roller type one-way clutch, in order to obtain positive engagement, each of the rollers as torque transmitting members is biased by the associated spring to be engaged with the cam surface. In order to engage the rollers with the cam surfaces positively, it is important that the plurality of rollers be operated in synchronous with each other.
Particularly, in a roller type one-way clutch for a motor bike, since the number of rollers is small (for example, three or six), if all of the rollers are not engaged with the corresponding cam surfaces positively, a design torque capacity may not be obtained.
Japanese Patent Application Laid-open No. 2003-172377 discloses a technique in which holder portions are provided in pockets to prevent the rollers and the springs from dislodging toward the inner peripheral side of the inner race. However, this document does not teach an arrangement for synchronizing the plurality of rollers positively.
If a function of the spring for biasing the roller is worsened or stopped partially or entirely, the rollers cannot be synchronized with each other thereby to lose the reliability of the engagement, which affects a bad influence upon the stability of the operation of the roller type one-way clutch.